Tunable load sharing arch bridge

Abstract

A method and apparatus for adjusting the live and dead load balance between the arches of an arch bridge and the truss girder that supports the bridge deck. The method is achieved by providing hanger rods disposed between the arches and the top chords of the truss girder whose compression may be adjusted. In which the arch truss counter act the compression in the top chord of the truss. This interaction adds to the strength and safety of both elements of the structure. With this interaction there are no critical members which can cause catastrophic failure of the bridge by failing. By combining two of these bridges side by side, and then connected with the lateral members, both at top and bottom chord of trusses, it is possible to carry vehicular, train, and pedestrian lanes separated and accommodated with safety; all without a critical member.

What is claimed is: 
     
       1. A bridge structure comprising,
 a pair of structural arches each having first and second terminal ends, 
 a pair of truss beams disposed beneath the respective arches, each truss beam having longitudinally extending top and bottom chords, at least a portion of the length of which define a geometric chord of each arch, and where each top chord is attached to the terminal ends of the arch below which the truss beam is disposed, 
 a plurality of spaced apart tension rods interconnecting each arch and the respective top chord of the truss beam, 
 a plurality of first floor joists interconnecting the bottom truss chords, and 
 a road deck supported by the first floor joists.